1. Field of the Invention
The present invention relates to a method of producing a transversely aligned web in which filaments spun at a high rate are aligned in the transverse direction and an apparatus for implementing the method of the same. The transversely aligned web is utilized as a raw material web of a transversely stretched nonwoven fabric. Further, the transversely aligned web is utilized as a raw material web for producing a cross laminated nonwoven fabric in which a transversely stretched nonwoven fabric is laid on a longitudinally aligned nonwoven fabric or the like so that the aligning directions thereof cross to each other.
2. Description of the Related Art
Most of the conventional nonwoven fabric is a random nonwoven fabric in which alignment of filaments composing the nonwoven fabric is random. Therefore, the tensile strength thereof is weak and the dimension of the product is unstable. As an invention made for improving such drawback which the conventional nonwoven fabric encounters, there can be introduced Japanese Patent Publication No. 36948/91, Japanese Patent No. 2612203, Japanese Patent Publication No. 6126/95 or the like filed by the present applicant. According to the above publications, there is introduced a lamination type nonwoven fabric in which at least two sheets of nonwoven fabric as a raw material are stretched and the sheets of nonwoven fabric are laid on and bonded to one another so that the directions of stretching thereof cross to each other. Also, a method of producing such a nonwoven fabric is introduced in the above publications.
Japanese Patent Publication No. 36948/91 discloses a method of producing nonwoven fabric in which un-oriented filaments are spun to produce a long-fiber nonwoven fabric, and the resulting nonwoven fabric is stretched in one direction under a proper temperature so that the fabric tends to contain a larger rate of filament components aligned in one direction. Also in the patent publication, there is disclosed a method in which sheets of nonwoven fabric stretched by the above method are laid on each other so that the stretching directions of the nonwoven fabrics cross to each other.
Further, Japanese Patent Publication No. 36948/91 discloses a method of producing a long fiber nonwoven fabric in which the nonwoven fabric is produced by using un-oriented filaments aligned in one direction. According to the method of producing the long fiber nonwoven fabric, initially, filaments are produced by extrusion through a nozzle which is provided above a screen mesh running in one direction. Then, the filaments are dispersed by a heated airflow which flows spirally. Further, a pair of airflows are created below the nozzle so that the airflows collide with each other. The rotated spun filaments are further dispersed by the spreading airflow resulting from the collision of the airflows. In this case, if the moving direction of the airflows colliding with each other is in parallel with the running direction of the screen mesh, then the spun filaments are dispersed in a direction perpendicular to the running direction of the screen mesh. Thus, dispersed filaments are piled on the screen mesh and a piece of nonwoven fabric can be created on the screen mesh so that a majority of filaments are aligned in the transverse direction of the fabric. In this way, nonwoven fabric mainly containing filaments aligned in the transverse direction is produced. Conversely, if the moving direction of the airflows colliding with each other is substantially perpendicular to the running direction of the screen mesh, then the spun filaments are dispersed in a direction in parallel with the running direction of the screen mesh. Thus, when dispersed filaments are piled on the screen mesh, a piece of nonwoven fabric can be created on the screen mesh so that a majority of filaments are aligned in the longitudinal direction of the fabric. In this way, nonwoven fabric mainly containing filaments aligned in the longitudinal direction is produced.
Japanese Patent No. 2612203 discloses a method of producing a nonwoven fabric in which fibers are blown off together with a fluid from a blowoff nozzle toward an upper surface of a running belt-conveyor, and the fibers are piled so that the fibers can be aligned in one direction on the upper surface of the belt conveyor, thus a web having fiber aligned therein can be produced. According to one example of the method of producing fabric, at least a part of the belt conveyor is bent downwardly in a direction perpendicular to the running direction thereof, and the fluid and fibers are blown off toward the bottom portion of the bent groove portion of the conveyor belt. Then, the fluid blown off from a blowoff nozzle is dispersed in the direction in which the groove of the conveyor belt extends, whereby fibers are aligned in the dispersing direction.
Japanese Patent Publication No. 6126/95 discloses a method of producing a nonwoven fabric in which a spray spinning is employed so that a plurality of filaments are aligned in substantially one direction to form a one-direction aligned nonwoven fabric. According to the method of producing fabric, when a high molecular compound is blown off through a nozzle to spin filaments, the spun filaments are rotated or vibrated in the width direction. Then, at least a pair of air-flows substantially bilaterally symmetrical with respect to the side of the filaments are applied to filaments from the side of the filaments at the center of one filament rotated or vibrated, under condition that the rotated or vibrated filament has a draft property of two times or more. Thus, at least a pair of airflows are applied to filaments so that the filaments are dispersed in a direction perpendicular to the spinning direction of the filament while the filament is applied with draft. In this way, filaments are aligned in the direction in which the filaments are dispersed, and the filaments are piled in stratum, and the one-direction aligned nonwoven fabric can be produced.
The nonwoven fabric produced by the above methods has a high tensile strength. Moreover, since the filament composing the nonwoven fabric has a small diameter of 5 xcexcm to 15 xcexcm after subjecting it to the stretching process, its feeling of touch is smooth and the texture is flexible and soft. Furthermore, the nonwoven fabric is glossy and suitable for printing. In other words, owing to the minute filament diameter, the nonwoven fabric is proper texture. In addition, owing to high tensile strength, the nonwoven fabric provides desirable practical utility in spite of the fact that the thickness thereof is small.
Although the nonwoven fabric produced by the above-described methods disclosed in respective publications has a high tensile strength and proper texture, the productivity of the nonwoven fabric according to the above methods is still unsatisfactory. Therefore, it is necessary to improve the productivity for reducing the cost of the nonwoven fabric. For this reason, in order that the productivity of the producing apparatus disclosed in the above publications and the cost is reduced, it is necessary to develop a spinning means for spinning filaments of a transversely aligned web in which filaments are aligned in the transverse direction. Further, in addition to the improvement of productivity in spinning the filaments, it is necessary to enlarge the tensile strength of the transversely aligned web formed of the obtained filaments while the high productivity is maintained.
If the diameter of the filament of the product at the final stage is predetermined, to improve the productivity of the filaments by a single cone restrictively requires to increase the spinning rate of filaments by the single cone. According to a conventional method of spinning filaments at a high rate, as is disclosed in a reference entitled xe2x80x9cThe Newest Spinning Technologyxe2x80x9d (edited by Japanese Conference of Fiber Industry) published by High Molecular Publication Union, the limit rate of spinning is 10000 m/min. on an industrial base. When a transversely aligned web having a large width in which filaments are aligned in the transverse direction is produced, it is requested that the filaments are spun at a rate, e.g., 30000 m/min. to 100000 m/min. or more, far exceeding that rate which has been regarded as a limit so far.
However, to produce the nonwoven fabric only at a high productivity is meaningless, i.e., the produced nonwoven fabric shall have a proper characteristic. That is, it is necessary that the diameter of the filaments is small enough to make the fabric have a proper texture as a transversely aligned web. More concretely, it is necessary that the diameter of the filament soon after spinning falls within a range of from 10 xcexcm to 30 xcexcm, more desirably, to 25 xcexcm. Further, if the transversely aligned web formed of filaments is stretched in the transverse direction to produce a transversely stretched web, it is ideal that the transversely stretched web has a tensile strength in the stretching direction of 132.5 mN/tex (1.5 g/d) or more. Desirably, the transversely stretched web is requested to have a tensile strength of 158.9 mN/tex (1.8 g/d) or more. More desirably, the transversely stretched web is requested to have a tensile strength of 176.6 mN/tex (2.0 g/d) or more. Further, since the transversely aligned web or the transversely stretched web is utilized as a nonwoven fabric, the spinning means is requested to produce the web which is free from a defect portion such as pilling due to breaking of filament.
Therefore, an object of the present invention is to provide a transversely aligned web in which spun filaments are aligned in the transverse direction and which makes it possible to have a high productivity rate, and hence a low production cost.
Another object of the present invention is to propose a method of producing such a transversely aligned web, an apparatus to produce the same, and a spinning head utilized in the apparatus for producing such a web.
Another object of the present invention is to provide a transversely aligned web in which the tensile strength in the transverse direction of the transversely aligned web is high and proper texture as a fabric is maintained in spite of the fact that the productivity rate for the web is high.
Still another object of the present invention is to propose a method of producing such a transversely aligned web and an apparatus for producing the same in spite of the fact that productivity for producing the web is high.
In order to attain the above object, there is provided a transversely aligned web having filaments aligned in a transverse direction, wherein the filaments are spun at a rate of 30000 m/min. or more, the filaments extend continuously from one edge to the other edge in the width direction of the transversely aligned web, and the width thereof is 300 mm or more.
According to the transversely aligned web of the present invention, the filaments forming the transversely aligned web are spun at a rate of 30000 m/min. or more, which is remarkably larger than the rate of a conventional high-rate multi-filament spinning machine, for example. Therefore, there can be obtained a transversely aligned web which makes it possible to produce at a high productivity and with a low cost. Further, according to the transversely aligned web of the present invention, the filaments composing the transversely aligned web extend continuously from one edge to the other edge in the width direction of the transversely aligned web, and the width thereof is 300 mm or more. Therefore, the transversely aligned web is suitable for use as a transversely aligned nonwoven fabric, unlike a web having a defect portion such as pilling due to breaking of filament. Moreover, since the filaments extend continuously from one edge to the other edge in the width direction of the transversely aligned web, the transversely aligned web becomes wide and has a large tensile strength and elongation in the transverse direction of the transversely aligned web in spite of the fact that the productivity rate for the web is high. Furthermore, the above transversely aligned web is suitable as an original web when the original web is stretched in the transverse direction to produce a transversely stretched nonwoven fabric.
According to the present invention, it is preferable for the filament to have a diameter of a range of from 10 xcexcm to 30 xcexcm, and for the transversely aligned web to have an elongation of 70% or more in the transverse direction.
With the above property, when the transversely aligned web is utilized as an original web for forming a transversely stretched nonwoven fabric, it is possible to produce a transversely stretched nonwoven fabric which has a sufficiently large width, a desired texture and flexible and soft nature.
According to the present invention, the transversely aligned web may be stretched in the transverse direction, and further, it is preferable for the filaments composing the stretched transversely aligned web to have a diameter of a range of from 5 xcexcm to 15 xcexcm, and the tensile strength of the stretched transversely aligned web in the stretching direction is preferably 132.5 mN/tex (1.5 g/d) or more.
As described above, the transversely aligned web stretched in the transverse direction is formed of filaments of which diameter falls in the range of from 5 xcexcm to 15 xcexcm, and the tensile strength of the stretched transversely aligned web in the stretching direction is 132.5 mN/tex or more. Therefore, the transversely stretched nonwoven fabric according to the present invention provides a soft feeling of touch and has a high tensile strength in the transverse direction. The transversely stretched nonwoven fabric is suitable as an original web for producing a cross laminated nonwoven fabric in which the transversely stretched nonwoven fabric is laid on a longitudinally aligned nonwoven fabric or the like so that the aligning directions of filaments of respective nonwoven fabrics cross to each other.
According to the method of producing a transversely aligned web and apparatus for producing a transversely aligned web, initially, a melted resin is extruded from a spinning nozzle having an inner diameter of 0.6 mm or more downwardly. At the open end of the spinning nozzle, there is formed a annular primary airflow nozzle having a diameter of 2.5 mm or more so as to be concentric with the opening end of the spinning nozzle, and a primary airflow is blown off at a high temperature and at a high velocity in the gravitational direction, whereby a melted filament extruded from the opening end of the spinning nozzle is vibrated. Thereafter, secondary airflows at a high temperature are blown off from secondary airflow nozzles, which are disposed on the upstream side and the downstream side of the running direction of the conveyor with respect to the melted filament, toward the extruded melted filament vibrated by the primary airflow. Thus, the secondary airflows collide with each other below the spinning nozzle.
In this way, the extruded melted filament vibrated by the primary airflow can be flowed together with the secondary airflows which collide with each other and are spread in the width direction of the conveyor. Thus, the extruded melted filament vibrated by the primary airflow can be spread by the secondary airflows, with the result that it becomes possible to spin the filaments deriving from solidifying of the extruded melted filament, at a high rate of 30000 m/min. or more.
Then, the extruded melted filament is spread in the width direction of the conveyor, whereby the spun filaments are aligned in the width direction of the conveyor and piled on the conveyor. Thus, production is carried out for producing a transversely aligned web having filaments aligned in the width direction of the conveyor and extending in one direction along the running direction of the conveyor.
According to the process of producing the transversely aligned web, since filaments can be spun at a high rate of 30000 m/min. or more, the productivity of the transversely aligned web can be improved and hence the cost of the transversely aligned web can be decreased. Moreover, it becomes possible to produce the transversely aligned web in which filaments extend from one edge to the other edge of the transversely aligned web in the width direction thereof, and it becomes possible to widen its width up to 300 mm or more.
In order to improve the productivity of the transversely aligned web, it is necessary to array a number of spinning heads above the conveyor. According to the present invention, filaments can be spun at a high rate by a single spinning head. Therefore, the necessary number of spinning heads to be arrayed above the conveyor can be reduced. Thus, with the method of and apparatus for producing a transversely aligned web according to the present invention, it becomes possible to reduce the cost of facility and floor area to be prepared for the facility. Moreover, since the necessary number of spinning heads to be arrayed above the conveyor can be reduced, it is expected that the number of heads subjected to adjustment can also be reduced. Therefore, the method of and apparatus for producing a transversely aligned web according to the present invention are advantageous in terms of adjustment and maintenance of facility. Furthermore, the method of and apparatus for producing a transversely aligned web according to the present invention can provide high productivity in producing the transversely aligned web but also a merit that a transversely aligned web acquires a large width.
In the description of the present invention above and below provided for explaining the aligning direction of the filaments of the nonwoven fabric or stretching direction of the nonwoven fabric, the term xe2x80x9clongitudinal directionxe2x80x9d means a direction in which the nonwoven fabric is conveyed upon producing the nonwoven fabric, and the term xe2x80x9ctransverse directionxe2x80x9d means a direction perpendicular to the longitudinal direction, i.e., the width direction of the nonwoven fabric.
In the description of the present invention above and below, the term xe2x80x9celongationxe2x80x9d is in conformity with JIS (Japanese Industrial Standard)-L1095. That is, a web of a width of 5 cm is held so as to extend over a distance of 10 cm in the longitudinal direction and stretched at a tensile velocity of 10 cm/min. Then, the rate of stretching length to its original length upon breaking the web is expressed in a manner of %.
Further, it is a custom that the tensile strength of the web or the nonwoven fabric is expressed as a breaking strength, or a breaking load per 5 cm which is determined by a long fiber filament nonwoven fabric testing method based on JIS-L1096. However, in the description of the present invention above and below, since the mass per area of the nonwoven fabric under test is variously selected, the mass of the nonwoven fabric is converted into denier (tex) and the tensile strength is expressed by a strength per unit tex (mN/tex). A strength per unit denier (d) is denoted as a reference in addition to the strength per unit tex (mN/tex).
The above and other objects, features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings which illustrate examples of the present invention.